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Paul Huard is an educator, analyst and historian, who writes about the military, foreign policy and U.S. political history.

The M-3 being used by soldiers in World War II.

The M3 was born out of the necessity to put inexpensive sub-machine guns in the hands of American soldiers and Marines quickly and cheaply.Dubbed the ‘Grease Gun’ by GI’s, the M-3 developed a reputation that kept it in the U.S. military inventory from World War II all the way through to Desert Storm in 1991.

It was supposed to serve as a replacement to the iconic and expensive Thompson sub-machine gun, but it looked more like a mechanic’s tool than the product of advanced American industrial know-how.The M-3 was a practical weapon, with close-range stopping power. By the Korean War, the M3 was used in greater numbers than the Thompson.

In the 21st century, we are used to weapons made of exotic materials and that possess highly-technological features that maximize killing power–polymers and aerospace metals, lasers and optics.

But during World War II, there was a desperate urgency to manufacture vast quantities of weapons as quickly and cheaply as possible. The materials then looked like they were on sale at the corner hardware store.

M3 Sub machine Gun

The M-3: Rough and ready

The British overcame this need by producing the Sten Gun, a 9-by-19-millimetre sub-machine gun composed of steel tubing and sheet metal and which bears a similarity to a piece of plumbing.

The Russians developed the PPSh, a 7.62-by-25-millimetre sub-machine gun that unskilled laborers produced in auto shops.

The M-3 is an ugly hunk of metal – words like “crafted” or “elegant” simply do not apply to its design. It was made from stamped metal parts, like a General Motors car – not surprising when you remember the M-3 was developed by the automobile headlight division at G.M. in 1942.

The gun itself has no adjustable sights, no selector switch, no fine-grained wood furniture and few milled-steel components. It was welded together, and the user could see the welds on the weapon’s exterior. Even the butt stock was a simple U-shaped length of heavy wire. It was also a beast to carry, weighing nearly 11 pounds with a full 30-round magazine.

The 'poor man's' Tommy Gun

Yet the simplicity of the M-3’s manufacture lead to a distribution of more than 600,000 guns during World War II alone.

Another reason for the M-3’s popularity was that it spewed .45-caliber ACP bullets at 450 rounds per minute. It was also simple to operate, compact, because the butt-stock collapsed, and it was disposable.

That’s right, it was disposable. Until 1944, soldiers and Marines whose M-3s got damaged in battle simply threw them away and drew a new weapon from the armory. No one thought it was worthwhile to manufacture spare parts for the gun.

The M-3 saved the government money. The iconic Thompson sub-machine gun–a sleek, well-made weapon prized by any G.I. who could get his hands on one – cost Uncle Sam about $225 each. That’s around $3,000 a weapon today when you adjust for inflation. A new Grease Gun cost the government about $20 each, or about $260 a weapon in today’s dollars. No wonder it also bore the nickname “the poor man’s Tommy Gun.”

Machine gun movie star

Soldiers didn’t embrace the M-3 at first. But once the gun’s awkward cocking handle was eliminated, and they discovered its stopping power, G.I.s and Marines developed a sort of grudging affection for the gun.

The M-3 survived the Korean War and into the Vietnam War. US helicopter pilots often carried one in their cramped cockpits because it was smaller than an M-16, and offered more firepower than a pistol.

The M-3 even developed a kind of bad-boy reputation because of its prominence in the popular film The Dirty Dozen. In one famous scene, Lee Marvin’s character fires an M-3 at the criminals and misfits he is transforming into a fighting unit while they train on an obstacle course.

The last time the M-3 went to war as an official member of the US inventory was during Desert Storm in 1991, nearly 50 years after the military first introduced it to save money.